The present invention relates generally to a gripping element for a sports shoe or boot.
For the sake of simplicity herein, the term sports shoe will be used to cover any appropriate form of sports shoe, sports boot (being generally of a heavier construction than a sports shoe in the narrow sense) and the like.
There are many different forms of sports shoes having gripping elements or projections on the underneath of the sole thereof, for example for use in field-type sports such as football and the like. One of the problems which arises in regard to gripping elements on the soles of sports shoes are that the gripping elements tend to wear away, particularly when the person wearing the shoes walks across hard surfaces such as concrete, for example when gaining access to the playing field, and that in turn can cause the gripping elements to wear in such a way that they then have sharp edges and projections which can be the cause of possibly serious injury to other players.
In an effort to increase the operating life of such gripping elements and also to prevent the occurrence of sharp edges on the gripping elements due to wear thereof, with the attendant danger of injury, it has been suggested that ceramic inserts consisting for example of aluminum oxide, silicon carbide, tungsten carbide and the like, might be inserted into the elements, in order to make use of the high level of resistance to wear of ceramic materials. However, such gripping element constructions have not yet resulted in use of such gripping elements in practical situations, for two primary reasons, namely that it is very difficult to connect the ceramic insert to the body of the gripping element in such a way that the connection therebetween is capable of reliably withstanding the forces acting thereon in use of the sports shoe on which the gripping element is provided, and secondly, it is very difficult to keep the manufacturing cost at a level such that a ceramic gripping element is actually a viable proposition in comparison with gripping elements of conventional configurations. For example, in one form of gripping element having a ceramic insert, as set forth in German laid-open application (DE-OS) No 32 33 900, an oxide ceramic insert is injected directly into the body of the gripping element which consists of plastic material, or is secured therein by adhesive means. Experience in a practical situation has shown however that that form of connection between the ceramic insert and the body of the gripping element is not capable in the long term of withstanding in particular the thrust or shear forces which act perpendicularly to the longitudinal axis of the gripping element, with the result that the ceramic inserts come loose and are then lost.
In the face of that problem, it has been envisaged that a gripping element for a sports shoe may be provided which does not have a ceramic insert therein but in which the body of the gripping element also consists of ceramic material, as set forth in above-mentioned DE-OS No 32 33 900. Thus at its upper end, the body of the gripping element disclosed therein has a flange-like enlarged portion and openings or notches extending through the flange-like portion, and it is embedded in a carrier member of glass fibre-or carbon fibre-reinforced polyamide. In that arrangement, the plastic material of the carrier member is intended to penetrate into or through the openings or notches in the gripping element body portion and in that way fix it in position. The gripping element can then be fixed directly in the sole of a sports shoe by being embedded therein, by means of the above-mentioned plastic carrier member.
However, that gripping element construction is so expensive that it cannot be viably considered for use in relation to gripping elements which are to be low-cost articles.